Charging protocols may seem like a difficult concept to grasp, but if we translate them into everyday problems—such as: why does the same charging cable produce different charging results for different phones; why does the same adapter charge faster for one phone than another; and why are original cables better than other cables purchased later?—the core of these questions lies in the charging protocol. Simply put, the charging protocol acts like a translator between the adapter and the device, facilitating more efficient and accurate communication between them.
What is the charging protocol?
Before understanding charging protocols, we need to understand the charging process itself. Charging is a process of gradually converting external electrical energy into the chemical energy inside the device by controlling voltage and current. In this process, the charging protocol plays a crucial role. Without a charging protocol, issues such as battery overheating and slow charging may occur. A charging protocol is a set of negotiation rules that coordinate the voltage and current output and receiving methods between the adapter and the device. Under these rules, both the adapter and the device can find the most suitable charging method, reducing energy waste and ensuring safety during charging. The charging protocol itself does not generate electricity, nor is it a voltage or current source; it is a set of rules that allow the adapter and device to cooperate.
How do charging protocols work?
The charging protocol performs different functions at different times during the entire charging process.
At the start of charging
When the data cable is first plugged in, the adapter will not output a large amount of power, only a safe and low-risk output. The charging protocol comes into play at this time. It receives signals from the adapter, understands the power supply methods the adapter can provide, and allows the adapter to declare its capabilities. Then, it feeds this information back to the device. The device, based on its current battery level, maximum acceptable voltage, and current battery temperature, decides which power supply method to choose and relays its selection back to the adapter via the charging protocol.
During charging
After receiving feedback from the device via the charging protocol, the adapter adjusts its output power, increasing voltage or current to initiate fast charging. Throughout the charging process, the device constantly monitors its status. If it overheats or is nearing full charge, the device sends feedback to the adapter via the charging protocol to appropriately reduce current or voltage. Towards the final stage of charging, the charging protocol continues to coordinate between the two devices, gradually reducing power to achieve a constant voltage state until the battery is fully charged.
Throughout the charging process, the charging protocol plays a command and coordination role, ensuring that the entire charging process is efficient and safe.
Classification system of charging protocols
There are many charging protocols on the market, which can be mainly divided into five categories: USB standard protocols, fast charging protocols led by chip manufacturers, proprietary fast charging protocols of mobile phone manufacturers, traditional identification-based charging protocols, and wireless charging protocols. We can use a table to simply classify them:
|
Protocol Category |
Protocol Name |
Chinese/Full Name Description |
Adjustment method |
Typical power range |
Main use cases |
compatibility |
|
USB standard class protocol |
USB Power Delivery 2.0 |
USB Power Delivery Protocol 2.0 |
Multiple fixed voltage levels |
18W–60W |
mobile phones, tablets, and laptops |
high |
|
USB Power Delivery 3.0 |
USB Power Delivery Protocol 3.0 |
Fixed voltage + Programmable |
18W–100W |
mobile phones, tablets, and laptops |
high |
|
|
USB Power Delivery 3.1 |
USB Power Delivery Protocol 3.1 |
Fixed voltage + Programmable |
28W–240W |
High-performance laptops and monitors |
high |
|
|
Fast charging protocols led by chip manufacturers |
Programmable Power Supply |
Programmable power supply mode (part of PD) |
Continuously adjustable voltage |
20W–100W+ |
New generation of fast charging mobile phones |
high |
|
Qualcomm Quick Charge 1.0 |
Qualcomm Fast Charge 1.0 |
Fixed voltage |
≤10W |
Early Android phones |
middle |
|
|
Qualcomm Quick Charge 2.0 |
Qualcomm Fast Charge 2.0 |
Multiple fixed voltage levels |
18W |
Android phones |
middle |
|
|
Qualcomm Quick Charge 3.0 |
Qualcomm Fast Charge 3.0 |
Microstep voltage regulation |
18W–36W |
Android phones |
middle |
|
|
Qualcomm Quick Charge 4 / 4+ |
Qualcomm Fast Charge 4/4+ |
Based on USB PD |
27W+ |
Android phones |
high |
|
|
Mobile phone manufacturers' proprietary fast charging protocols |
Fast Charge Protocol |
Huawei fast charging protocol |
Fixed voltage |
18W–22.5W |
Huawei phones |
Low |
|
Super Charge Protocol |
Huawei SuperCharge Protocol |
High current scheme |
40W–100W+ |
Huawei phones |
Low |
|
|
VOOC Flash Charge |
OPPO Flash Charge Protocol |
Low voltage, high current |
30W–80W+ |
OPPO / OnePlus |
Low |
|
|
SuperVOOC |
OPPO SuperVOOC Flash Charge |
Low voltage, high current |
100W+ |
OPPO / OnePlus |
Low |
|
|
FlashCharge |
vivo Flash Charge Protocol |
Multiple options |
33W–120W |
vivo mobile phone |
Low |
|
|
Xiaomi Fast Charge |
Xiaomi Fast Charging |
Hybrid scheme |
33W–120W+ |
Xiaomi phones |
Low |
|
|
Traditional identification-based charging protocols |
USB Battery Charging DCP |
USB Battery Charging Specification (Dedicated Charging Port) |
No negotiation |
≤12W |
Old equipment, charging heads |
Very high |
|
Apple 2.4A Charging |
Apple 2.4A charging recognition |
Voltage identification |
≈12W |
Older iPhones / iPads |
middle |
|
|
Wireless charging protocol |
Qi Wireless Charging |
Qi wireless charging standard |
Agreement negotiation |
5W–15W |
mobile phones, earphones |
high |
|
MagSafe |
Apple magnetic wireless charging |
Agreement negotiation |
15W–25W |
iPhone |
middle |
The key to maximizing the effectiveness of charging protocols: the data cable.
Charging cables play a crucial role in charging protocols. They are more than just cables; they directly affect whether fast charging is possible, the wattage of fast charging, and the stability and safety of the entire charging process. Many fast charging protocols require charging cables to function. A charging cable contains not only power cords but also other conductors. If the internal structure of the charging cable is substandard or the cable itself is incomplete, fast charging will fail. The charging cable also determines the maximum charging power. Even if the adapter and device support the charging protocol, insufficient wattage of the charging cable will prevent the desired power from being achieved. To achieve high-wattage fast charging, the cable needs an E-Marker chip. The E-Marker chip provides safety assurance for high-wattage fast charging, preventing cable burn-out. For example, the aulumu M07 features an E-Marker chip. The M07 is a full-featured USB 3.1 Type-C to Type-C cable that can charge various devices such as mobile phones, Bluetooth headsets, power banks, and tablets, and can also transfer data and mirror the phone screen. The cable is made entirely of nylon braided material, making it more durable and wear-resistant. Thanks to the E-Marker chip, the M07 can achieve a maximum charging power of 240 watts and supports multiple charging protocols, including standard USB charging protocols, chip manufacturer-led protocols, and some proprietary protocols from mobile phone manufacturers, thus meeting the needs of multiple devices simultaneously.
Charging protocols are an unavoidable communication medium during the charging process. Adapters and devices can communicate and confirm each other's status through charging protocols, ensuring efficient and safe charging. Data cables are the embodiment of this medium, allowing the charging protocol to be implemented more effectively. Both are crucial components throughout the entire charging process.
